1. Field of the Invention
The present invention relates to a method of producing a ferroelectric thin film-forming composition suitable for use in a high-capacity and high-density thin film capacitor or the like; and an application of the same
Priority is claimed on Japanese Patent Application No. 2013-061723, filed on Mar. 25, 2013, the content of which is incorporated herein by reference.
2. Description of Related Art
Japanese/Unexamined Patent Application, First publication No. S60-236404 (claim 1, line 14 in the lower left column of page 5 to line 16 in the same column of the same page) discloses a method of forming a ferroelectric thin film material. Specifically, first, one dielectric material-forming precursor selected from lead titanate (PT), lead zirconate titanate (PZT), and the like is dissolved in an organic solvent containing at least one selected from lower alcohols, β-diketones, and the like as a major component to prepare a dielectric material-forming precursor solution. Next, the dielectric material-forming precursor solution is coated on a metal substrate and dried to form a coating film of a dielectric material-forming precursor, and then the coating film is pre-baked in a temperature range from a decomposition temperature of an organic material in the coating film to a crystallization temperature of a dielectric material. Next, the coating, drying and pre-baking processes of the dielectric material-forming precursor solution are repeated, followed by baking at the crystallization temperature or higher of the dielectric material. Alternatively, the coating process of the dielectric material-forming precursor solution on a metal substrate, the drying process, and the baking process of the dielectric material at the crystallization temperature or higher of the dielectric material are repeated. As a result, two or more layers of thin films of lead titanate (PT), lead zirconate titanate (PZT), and the like are formed on the metal substrate, thereby obtaining a ferroelectric thin film material. In the method of forming a ferroelectric thin film material having the above-described configuration, a dielectric material-crystallized thin film having a desired thickness, non-conductivity, and ferroelectricity can be formed on a metal substrate
However, when a PZT film having a thickness of 100 nm or greater per layer is formed using this method, there are problems in that cracking occurs and film density is decreased. In order to solve these problems, approaches have been taken in which, for example, a high-molecular compound, an drying control chemical additive (DCCA), crystalline fine powder, or the like is added to a solution to release stress (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2001-261338 (claim 1, paragraphs [0016] to [0024], Table 1) and J Sol-Gel Sci Technol (2008) 47:316 to 325).